Plastic planter flat

ABSTRACT

A compartmented tray thermoformed from a sheet of thermoplastic material and having at least two rows of compartments, adjacent compartments in each row being separated by cross ribs. A reinforcing rib extends continuously from one end of the tray to the opposite end thereof joining the pair of adjacent rows. Each of the cross ribs and the reinforcing rib have a substantially inverted U-shaped cross section and the height of the reinforcing rib is greater than the height of the cross ribs to provide a reinforcing structure transverse to each of the cross ribs to strengthen the tray against bending. The cross ribs in one row of compartments are offset with respect to the cross ribs of an adjacent row of compartments but in each row all of said cross ribs are modularly spaced.

1111M tates atent 1 3,751,852

Schrepper Aug. 14, 1973 [54] PLASTIC PLANTER FLAT 3,561,158 2/l97l Marcan 47/34.13

[75] Inventor: Gerald A. Schrepper, Kalamazoo, FOREIGN PATENTS OR APPLICATIONS Mlch- 2,017,100 10/1970 Germany 47 3413 [73] Assignee: Fabri-Kal Corporation, Kalamazoo,

Mi h Primary Examiner-Robert E. Pulfrey Assistant Examiner-R. T. Rader [221 1971 Attamey-Woodhams, Blanchard and Flynn [21] Appl. No.: 115,013

[ STRACT [52] US. Cl 47/34.l3, 220/23.6, 229/25 A compartmented tray thermoformed from a sheet of [51] Int. Cl A01g 9/02 thermoplastic material and having at least two rows of [58] Field of Search 47/34.l3, 37; compartments, adjacent compartments in each row 220/23.6, 23.2, 21, 22, 72, 97 D; 229/25 being separated by cross ribs. A reinforcing rib extends continuously from one end of the tray to the opposite [56] References Cited end thereof joining the pair of adjacent rows. Each of UNITED STATES PATENTS the cross ribs and the reinforcing rib have a substantially inverted U-shaped cross section and the height of l the reinforcing rib is greater than the height of the cross 3:502:24] 3/1970 smithmw: H 220/23'6 ribs to providea reinforcing structure transverse to 3,499,525 970 Kama, ,21 X each of the cross ribs to strengthen the tray against 2,75 8,742 8/1956 Farrell 220/21 bending. The cross ribs in one row of compartments are 3,101,864 8/1963 (Hickman... 220/72 X offset with respect to the cross ribs of an adjacent row 2,913,379 59 Lurie 220/72 X of compartments but in each row all of said cross ribs 2,508,445 5/1950 Celia 220/72 x are modular, spaced. 3,563,445 2/1971 Clayton 220/72 X 3,480,178 ll/l969 Morgan 220/21 X 11 Claims, 6 Drawing Figures .7/ J 7 .7/ 35 J zv 17 112 I6 Z 27 Yr PLASTIC PLANTER FLAT FIELD OF THE INVENTION This invention relates to a compartmented tray and, more particularly, relates to a thermoformed thermoplastic planter flat having a plurality of compartments therein defining a modular system for receiving a planter liner having a shape adapted to be received in the compartmented tray.

BACKGROUND OF THE INVENTION Thermoformed trays have been proposed for many uses, but in general have been restricted to carrying relatively light loads. This problem arises from the fact that in elongated compartmented trays wherein the compartments are in lateral alignment, there-is only a small resistance to bending along the line of compartment separators. This lateral alignment, however, follows in the prior art from the necessity of the tray being able to receive a liner having compartments of equal size and spacing.

One design for meeting this problem is setforth in Smith US. Pat. No. 3,502,241 which discloses a compartmented tray having two rows of compartments with adjacent compartments in each row being separated by cross members which are colinear with the cross members which separate the corresponding adjacent compartments in the other row. As acknowledged in this patent, the colinear relationship between the cross members presents a'situation of only nominal resistance against bending along the line of the respective colinear cross members. As a result, it is necessary to provide a reinforcing feature which here comprises a longitudinal reinforcing member which joins the adja cent rows and has a height greater than the height of the cross members. Nevertheless, although the problem has been lessened by the provision of the central reinforcing rib, the existence of the colinear cross members still presents a bending problem along the line of the aligned cross members. This bending limits the usefulness of this type of tray and has in the prior art provided a continuing problem. i

I have discovered that the compartmented tray may be adequately and very simply strengthenedby a relocation of the cross members, namely by'offsetting same with respect to each other in adjacent rows while also spacing same in a modular manner to enable the tray to continue to receive liners having evenly spaced compartments. I have also discovered that the tray can be further strengthened by making the upper laterally extending contour of the cross members arcuate between ends thereof that are at different elevations to thereby resist a bending moment applied to the tray along an axis parallel to the longitudinal axis of the tray. Accordingly, the objects of this invention include:

I. To provide a compartmented therrnoformed tray incorporating an improved strengthening feature to prevent bending of the tray along a line transverse to the central reinforcing rib.

2. To provide a modular arrangement in the spacing between the cross ribs in each row to accommodate the reception of a liner tray having compartments of equal size and spacing.

3. To provide a compartmented tray which may be manufactured by vacuum-forming, and/or pressure forming, a sheet of thermoplastic material to the desired shape.

4. To provide a compartmented tray which may be manufactured by presently known devices.

Other objects and purposes of this invention will be apparent to persons acquainted with compartmented trays of this general type upon reading the following specification and inspecting the accompanying drawings, in which:

FIG. 1 is a perspective view of the compartmented tray embodying the invention and a liner member which is adapted to be received in the compartmented tray construction;

FIG. 2 is a top view of the compartmented tray;

FIG. 3 is a sectional view taken along the line IIIIII of FIG. 2;

FIG. 4 is a sectional view taken along the line IVIV of FIG. 2;

FIG. 5 is an enlarged fragmentary sectional view of the encircled portion A in FIG. 4; and

FIG. 6 is an enlarged fragmentary sectional view taken along the line VI-VI of FIG. 2. I

Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words up, down, right and left will designate directions in the drawings to which reference is made. The words in and out will refer to directions toward and away from, respectively, the geometric center of the device and designated parts thereof. Such terminology will include derivatives and words of similar import.

SUMMARY OF THE INVENTION A compartmented tray is therrnoformed from a sheet of thermoplastic material and has at least two rows of compartments, adjacent compartments in each row being separated by cross ribs. A reinforcing member extends continuously from one end of the tray to the opposite end thereof joining the pair of adjacent rows. Each of the cross ribs and the reinforcing rib have a substantially inverted U-shaped cross section and the height of the reinforcing member is greater than the height of the cross ribs to provide a reinforcing structure transverse to each of the cross ribs to strengthen the tray against bending. The cross ribs in adjacent rows are offset from each other but arranged modularly in each row in order to receive a compartmented liner wherein the compartments are of equal size and spacmg,

DETAILED DESCRIPTION Referring now to the drawings in detail, a tray 10 (FIG. 1 and 2) is therrnoformed from a sheet of thermoplastic material and comprises upstanding endwalls l1 and 13, sidewalls I2 and 14, and a bottom wall 16, all integrally connected together. The upper edge of each of the walls ll, l2, l3 and 14 is curled over as at 17 (FIG. 4). The curled upper edge I7 of each upstanding wall serves to strengthen the upper edges thereof and to resist a bending and/or flexing of the tray.

A longitudinal reinforcing rib 18 extends longitudinally of the tray and is parallel with and is positioned, in this embodiment, centrally between the upstanding sidewalls l2 and 14. The reinforcing rib 18 has an inverted U-shaped cross section and is integrally connected to the upstanding end walls 11 and 13 and the bottom wall 16. The height of the reinforcing rib I8 is less than the height of the upstanding walls ll, l2, l3 and 14.- v

The bottom wall 16 comprises a plurality of laterally spaced rows 21 of upstanding ribs 22 integrally formed therewith. The upstanding ribs 22 extend longitudinally of the tray parallel with the reinforcing rib 18. Each rib 22 is longitudinally spaced from an adjacent rib 22 to define a gap 23 (FIGS. 2 and 3). In this particular embodiment, each rib 22 has an inverted U-shaped cross section and is rounded at the longitudinal ends as at 24.

The bottom wall 16 also comprises a plurality of rows of laterally spaced and parallel ridges 26 on opposite sides of the reinforcing rib 18 which extend between and parallel to the ribs 22, the reinforcing rib 18 and the sidewalls 12 and 14. A plurality of longitudinally spaced holes 27 are provided in the ridges 26, which holes 27 are greater in diameter than the width of each of the ridges 26. In this particular embodiment, the ridges 26 are closely adjacent the upstanding sidewalls 12 and 14 and the reinforcing rib 18. An intermediate ridge 28 is provided on the bottom wall 16 which extends parallel between the pairs of rows of ridges 26 on opposite sides of the central reinforcing rib 18.

A plurality of cross ribs 31 are provided on one side of the reinforcing rib 18, which cross ribs 31 extend perpendicular to the sidewall 12 and the reinforcing rib 18 to define a row 19 of compartments divided by said cross ribs. Each cross rib 31 has an inverted U-shaped cross section and is integrally connected to the bottom wall 16, the reinforcing rib 18, the ribs 21 and the ridges 26 and 28. The height of the cross rib 31 adjacent the central reinforcing rib 18 is less than the height of the cenral reinforcing rib 18 to rigidify the container where the cross ribs are joined to the central reinforcing rib to prevent a bending on a transverse axis to the central reinforcing rib. The upper contour 32 of the cross rib 31 is generally arcuate and curves upwardly (FIG. 4) so that the end of the cross rib 31 adjacent the upstanding sidewall 14 is approximately equal in height to the height of the central reinforcing rib 18. The arcuate portion serves to prevent a hinging action about the line of the cross ribs 31.

A plurality of further cross ribs 34 are provided on the other side of the reinforcing rib 18, which cross ribs 34 extend perpendicular to the upstanding sidewall 14 and the reinforcing rib 18 and define a second row 21 of compartments divided by the cross ribs 34. The cross ribs 34, like the cross ribs 31, have an inverted U- shaped cross section and are integrally connected to the bottom wall 16, the ribs 21, the ridges 26 and 28, the upstanding sidewall 14 and the central rib 18. The height of the cross rib 34 adjacent the central rib 18 is less than the height of the reinforcing rib. The upper contour 36 of the cross rib 34 is generally arcuate and curves upwardly (FIG. 4) so that the end of the cross rib 34 adjacent the upstanding sidewall 14 is approximately equal in height to the height of the reinforcing rib 18. The arcuate portion serves to prevent a hinging action about the line of the cross ribs 34.

The foregoing construction of the cross ribs 31 and 34 also serve to prevent a bending of the tray about an axis parallel to the central reinforcing rib 18.

The cross ribs 31 and 3 in the compartmented tray 10 are offset from each other as illustrated in FIG. 2 and spaced from each other and from the end walls 11 and 13 distances which are multiples of a single spacing unit. Thus, in this embodiment, the distances from the end walls 11 and 13 to the respectively adjacent cross ribs 31 are both equal to the single spacing unit and the spacing of the remaining ribs 31 is twice said single spacing. Further, in this embodiment the spacing between the cross ribs 34, and between the end ones thereof and the end walls 11 and 13, is also twice said single spacing unit. Further, in this embodiment, the longitudinal spacing between a pair of cross ribs 31 is equal to twice the longitudinal spacing between a cross rib 31 in row 19 and the next adjacent cross rib 34 in row 21. Since the cross ribs 31 and 34 are not aligned with one another, the strength of the tray is substantially improved due to the lack of a continuous cross rib extending laterally across the width of the tray.

The longitudinal spacing between the ribs 31 and 34 thus defines a modular arrangement. The compartment 37 (FIG. 2), for example, defined by the upstanding wall 12, the central reinforcing rib 18 and two of the cross ribs 31 is of a size to receive two compartments of a compartmented liner, described below, the compartment defined between either end wall 11 or 13 and the nearest cross rib 31 will receive one compartment of such liner.

The liner 38 comprises a receptacle 39 having a pcripheral flange 40 is divided into a plurality of compartments 41 aligned in rows 42 and 43 and each are preferably interconnected to the other by a perforable connection 44 to permit each compartment 41 to be separated one at a time or in groups from the remainder of the liner 38. Each compartment 41 is adpated to receive seedlings 45 therein and each compartment 41 has a plurality of openings 46 in the bottom wall thereof to permit the seedlings to be watered with the excess water draining through the openings 46.

When the liner is inserted into the compartmented tray 10, as illustrated in dotted lines in FIG. 3, the liner will be supported by its flange 40 on the upper curled over edge 17 on the tray 10. The liner 38 is flexible enough so that it will sag and the bottoms of each of the compartments will rest on the ribs 22. A pair of compartments 41 in one of the rows 42 or 43 of the liner 38 will be located between the cross ribs 31 and 34 and single ones of such compartments will be located between the end walls 11 and 13 and the respectively adjacent cross'ribs 31. Thus, the longitudinal spacing between one cross rib 31 in one row and the next adjacent cross rib 34 in the adjacent row is equal to the width of one of the compartments 41 in the liner 38. Thus, the modular arrangement of the cross ribs 31 and 34 and their spacing from the end walls 11 and 13 is adapted to cooperate with the spacing arrangement between the compartments 41 of the liner 38.

Further, the cross ribs 31 and 34 serve to prevent a shifting of the liner 38 relative to the tray 10, such as might occur if the liner 38 is inadvertently snagged by a piece of equipment which places the seedlings 45 and/or the dirt in the compartments 41. More specifically, the longitudinally facing sides 48 (FIG. 3) of each of the compartments 41 engage the longitudinally facing sides of the cross ribs 31 or 34. As a result, sufficient of such compartments are restrained by the cross ribs 31 or 34 to deter a relative shifting between the liner 38 and the tray 10.

The spacing or gap 23 between the longitudinal ends of the ribs 22 permits the water which drips out through the hoies 46 in liner 38 to be able to drain out of the tray 10 through any of the holes 27. The ridges 26 having the holes 27 therein serve to define a path for the drained water after the water leaves the tray 10. That is, the bottom surface of the ridge 27 is lifted off the support surface as at 47 in FIG. 5 so that the water can flow toward the longitudinal ends of the tray or the nearest cross rib 31 or 34.

A plurality of stacking lugs 35 (FIGS. 2 and 6) are provided in each of the four corners of the tray 10 and serve to prevent a plurality of stacked trays from sticking together. Each stacking lug comprises a pocket 51 in each of the four corners of the adjoining sidewalls l1, 12, 13 and 14 to define a projection 52 which will rest on the next adjacent edge portion 17 on the next adjacent tray 10. Similarly, a plurality of stacking lugs 4 are provided in each of the comers of each of the compartments 41 of the liner 38 and serve to prevent a plurality of stacked liners from sticking together.

While the tray 10 has been illustrated with two rows 19 and 21 of compartments, any desired number of rows can be employed, with a reinforcing rib joining each pair of adjacent rows. lneach row, however, the number of cross ribs 31 or 34 will be unequal to the number of cross ribs in the next adjacent row. In the particular embodiment illustrated in FIG. 2, the number of cross ribs 31 exceeds the number of cross ribs 34.

Although a particular preferred embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A compartmented tray thermoformed from a sheet of thermoplastic material, comprising:

a pair of upstanding side walls and a pair of upstanding end walls and a bottom wall; an upstanding reinforcing rib integrally molded in said bottom wall and extending continously from one end of the tray to the opposite end thereof to define a pair of adjacent longitudinally extending rows on opposite sides of said reinforcing rib;

asymmetrical stiffening means disposed in said rows on opposite sides of said reinforcing rib, said asymmetrical stiffening means consisting of a plurality of upstanding first cross ribs integrally molded into said bottom wall for separating one of said rows into adjacent compartments and a plurality of upstanding second cross ribs integrally molded into said bottom wall for separating the other of said rows into adjacent compartments,

said second cross ribs being longitudinally spaced from and nonaligned with said first cross ribs in said one row to thereby define said asymmetrical stiffening means to effect a strengthening of said tray against bending along a line of the cross ribs.

2. A compartmented tray according to claim 1, including also a plurality of longitudinally extending rows each having a plurality of elongated, longitudinally spaced and upstanding first ribs in the bottom of said tray lower in height than and parallel to said reinforcing rib for effecting further longitudinal stiffening of said tray.

3. The compartmented tray defined in claim 2, including'also a plurality of longitudinally aligned, laterally spaced secondribs in the bottom of said tray extending parallel to said reinforcing rib and extending continuously between and perpendicular to said cross ribs and drain openings extending through said bottom arranged along said second ribs, said openings being of a diameter greater than the width of said second ribs.

4. The compartmented tray defined in claim 3, wherein the upper contour on each of said cross ribs is arcuate in shape.

5. The compartmented tray defined in claim 4, wherein the portion of each of said cross ribs adjacent the reinforcing rib is lower than the opposite end thereof adjacent one of said side walls.

6. The compartmented tray defined in claim 3, wherein the upper contour on each of said cross ribs is concavely arcuate.

7. The compartmented tray defined in claim 1, including means defining a plurality of stacking lugs on said tray to prevent a plurality of stacked trays from sticking together.

8. A compartmented tray thermoformed from a sheet of thermoplastic material, comprising:

a pair of upstanding side walls and a pair of upstanding end walls and a bottom wall;

an upstanding reinforcing rib integrally molded in said bottom wall and extending continously from one end of the tray to the opposite end thereof to define a pair of adjacent longitudinally extending rows on opposite sides of said reinforcing rib; asymmetrical stiffening means disposed in said rows on opposite sides of said reinforcing rib, said asymmetrical stiffening means consisting of a plurality of longitudinally spaced and upstanding first cross ribs integrally molded in said bottom wall and extending perpendicularly to and between a side wall of said tray and one side of said reinforcing rib to separate one of said two rows into compartments and a plurality of longitudinally spaced and upstanding second cross ribs integrally molded in said bottom wall and extending perpendicularly to and between the other side wall of said tray and the other side of said reinforcing rib to separate the other of said two rows into compartments, each of said second cross ribs being longitudinally spaced from and nonaligned with said first cross ribs in said one row to thereby define said asymmetrical stiffening means, said longitudinal spacing between said first and second cross ribs being equal to one half the spacing between said cross ribs in said first and second rows so that said symmetrical first and second cross ribs will effect a strengthening of said tray against bending along a line of the cross ribs.

9. A compartmented tray thermoformed from a sheet of thermoplastic material, comprising:

a pair of upstanding side walls and a pair of upstanding end walls and a bottom wall;

an upstanding reinforcing rib integrally molded in said bottom wall and extending continously from one end of the tray to the opposite end thereof to define a pair of adjacent longitudinally extending rows on. opposite sides of said reinforcing rib; asymmetrical stiffening means disposed in said rows on opposite sides of said reinforcing rib, said asymmetrical stiffening means consisting of a plurality of longitudinally spaced and upstanding first cross ribs integrally molded in said bottom wall and extending perpendicularly to and between a side wall of said tray and one side of said reinforcing rib to separate one of said two rows into compartments and a plurality of longitudinally spaced and upstanding second cross ribs integrally molded in said bottom wall and extending perpendicularly to and between the other side wall of said tray and the other side of said reinforcing rib to separate the other of said two rows into compartments, each of said second cross ribs being longitudinally space from and nonaligned with said first cross ribs in said one row to thereby define said asymmetrical stiffening means, the spacing between an end wall of said tray and the nearest cross rib in at least one of said first and second rows being equal to a single spacing unit, said single spacing unit being also and the number of said second cross ribs equals two.

UNITED STATES PATENT sim lar 4 CERTENCATE OF CORRECTFON Patent No. 3 751 852 Dated August 14 1973 lnv' n fl l Gerald A. Schrenner It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column Bf line 62; change "3" to .34- v Column4, line 3; after "spacing" (first occurrence) 7 insert --unit-. Column 5, line 2; change "27 to --26-- Q line 55; after "row" insert said first and second ribs being alternately positioned insaid longitudinal direction--.

I line 59 after "plurality" delete "of longitudinally extending rows' 'f f line6 0; delete "each having a plurality".

Signed and sealed this 12th day of March 1974.

(SEAL) Attest: EDWARD M.FLETCHER,JR, C. MARSHALL DANN Attest-ing Officer Commissioner of Patents FORM PO-105O (10-69) USCOMM'DC O376P69 U. S. GOVERNMENT HUNTING OFFICE I989 0-366-534, '5 

1. A compartmented tray thermoformed from a sheet of thermoplastic material, comprising: a pair of upstanding side walls and a pair of upstanding end walls and a bottom wall; an upstanding reinforcing rib integrally molded in said bottom wall and extending continously from one end of the tray to the opposite end thereof to define a pair of adjacent longitudinally extending rows on opposite sides of said reinforcing rib; asymmetrical stiffening means disposed in said rows on opposite sides of said reinforcing rib, said asymmetrical stiffening means consisting of a plurality of upstanding first cross ribs integrally molded into said bottom wall for separating one of said rows into adjacent compartments and a plurality of upstanding second cross ribs integrally molded into said bottom wall for separating the other of said rows into adjacent compartments, said second cross ribs being longitudinally spaced from and nonaligned with said first cross ribs in said one row to thereby define said asymmetrical stiffening means to effect a strengthening of said tray against bending along a line of the cross ribs.
 2. A compartmented tray according to claim 1, including also a plurality of longitudinally extending rows each having a plurality of elongated, longitudinally spaced and upstanding first ribs in the bottom of said tray lower in height than and parallel to said reinforcing rib for effecting further longitudinal stiffening of said tray.
 3. The compartmented tray defined in claim 2, including also a plurality of longitudinally aligned, laterally spaced second ribs in the bottom of said tray extending parallel to said reinforcing rib and extending continuously between and perpendicular to said cross ribs and drain openings extending through said bottom arranged along said second ribs, said openings being of a diameter greater than the width of said second ribs.
 4. The compartmented tray defined in claim 3, wherein the upper contour on each of said cross ribs is arcuate in shape.
 5. The compartmented tray defined in claim 4, wherein the portion of each of said cross ribs adjacent the reinforcing rib is lower than the opposite end thereof adjacent one of said side walls.
 6. The compartmented tray defined in claim 3, wherein the upper contour on each of said cross ribs is concavely arcuate.
 7. The compartmented tray defined in claim 1, including means defining a plurality of stacking lugs on said tray to prevent a plurality of stacked trays from sticking together.
 8. A compartmented tray thermoformed from a sheet of thermoplastic material, comprising: a pair of upstanding side walls and a pair of upstanding end walls and a bottom wall; an upstanding reinforcing rib integrally molded in said bottom wall and extending continously from one end of the tray to the opposite end thereof to define a pair of adjacent longitudinally extending rows on opposite sides of said reinforcing rib; asymmetrical stiffening means disposed in said rows on opposite sides of said reinforcing rib, said asymmetrical stiffening means consisting of a plurality of longituDinally spaced and upstanding first cross ribs integrally molded in said bottom wall and extending perpendicularly to and between a side wall of said tray and one side of said reinforcing rib to separate one of said two rows into compartments and a plurality of longitudinally spaced and upstanding second cross ribs integrally molded in said bottom wall and extending perpendicularly to and between the other side wall of said tray and the other side of said reinforcing rib to separate the other of said two rows into compartments, each of said second cross ribs being longitudinally spaced from and nonaligned with said first cross ribs in said one row to thereby define said asymmetrical stiffening means, said longitudinal spacing between said first and second cross ribs being equal to one half the spacing between said cross ribs in said first and second rows so that said symmetrical first and second cross ribs will effect a strengthening of said tray against bending along a line of the cross ribs.
 9. A compartmented tray thermoformed from a sheet of thermoplastic material, comprising: a pair of upstanding side walls and a pair of upstanding end walls and a bottom wall; an upstanding reinforcing rib integrally molded in said bottom wall and extending continously from one end of the tray to the opposite end thereof to define a pair of adjacent longitudinally extending rows on opposite sides of said reinforcing rib; asymmetrical stiffening means disposed in said rows on opposite sides of said reinforcing rib, said asymmetrical stiffening means consisting of a plurality of longitudinally spaced and upstanding first cross ribs integrally molded in said bottom wall and extending perpendicularly to and between a side wall of said tray and one side of said reinforcing rib to separate one of said two rows into compartments and a plurality of longitudinally spaced and upstanding second cross ribs integrally molded in said bottom wall and extending perpendicularly to and between the other side wall of said tray and the other side of said reinforcing rib to separate the other of said two rows into compartments, each of said second cross ribs being longitudinally space from and nonaligned with said first cross ribs in said one row to thereby define said asymmetrical stiffening means, the spacing between an end wall of said tray and the nearest cross rib in at least one of said first and second rows being equal to a single spacing unit, said single spacing unit being also equal to said longitudinal spacing between any pair of said longitudinally spaced first and second cross ribs so that said asymmetrical first and second cross ribs will effect a stengthening of said tray against bending along a line of said cross ribs.
 10. The compartmented tray according to claim 9, wherein the number of said first cross ribs in said one row is one greater than the number of said second cross ribs in said other row.
 11. The compartmented tray according to claim 10, wherein the number of said first cross ribs equals three and the number of said second cross ribs equals two. 